If you see the official Microsoft recommendation for the installation of XP Service Pack 2 (What to Know Before Downloading and Installing SP2) you can see what many sites are reporting in these days:
"Check your computer for spyware and other unwanted software before installing SP2".
Obviously, this is a foundamental recommendation (a security tool must be installed on a previous secure system to work correctly) but recommended to check your system with other products (such as Lavasoft Ad-aware) is not the best way to do for a big company like MS.
Why not developed an anti spam tool by itself, that could used for all their installation? This could be a good way to start working on security...